What is this close-up picture? (WotsThat: Bird eggshell)

Question

What object is shown in this zoomed-in close-up photo?

ThornPetal · Accepted Answer

Bird eggshell. Bird eggshells are incredibly strong despite being thin, thanks to their crystalline structure made primarily of calcium carbonate. The shell's color and pattern are determined by pigments deposited during the final stages of egg formation in the mother bird's oviduct.

Answer: Bird eggshell

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